Heat exchange apparatus for rectifying columns



June 6, 1939. P. PEFF 2,160,898

HEAT EXCHANGE APPARATUS FOR RECT IFYING COLUMNS Filed Match 16, 1938III! NITROGE'N ange INVENTOR. Mex" 5y,

ATTORNEY;

Patented June 6, 1939 PATENT OFFICE HEAT EXCHANGE APPARATUS FORRECTIFYIN G COLUMNS Peter Peif, West Orange, N. J. Application March 16,1938, Serial-N0. 198,192

3 Claims.

This invention relates generally to improvements in heat exchangeapparatus for use in rectifying columns for distilling atmosphericgases; and the invention has reference, morexparticu- -1arly, to a novelconstruction of heat exchange means adapted to form part of a rectifyingcolumn wherein air under pressure is rapidly cooled down, then expandedand liquefied, and thereupon distilled to separate its oxygen and mnitrogen components for discharge from the column.

In the -rectifying of atmospheric gases, air is first suitably purifiedand then compressed to a high pressure (usually from 500 to 3000pounds),

and after being dried is admitted into a rectifying column wherein it isexpanded to approximately atmospheric pressure and liquefied andthereupon distilled to separatethe oxygen and nitrogen.

Preparatory to the expansion, liquefication and distillation processes,the high pressure air admitted into the rectifying column at relativelyhigh temperature must first be rapidly cooled down. It is an object ofthis invention to pro- 25 vide a simply constructed but highly eflicientheat exchange apparatus'through which the ingoing and downflowing airinitially passes, and by means of which the, relatively cold outgoingand up-flowing oxygen and nitrogen gases, being discharged from therectifying column, may be effectively utilized to absorb or extract heatfrom the counter-flowing ingoing air. To this end the novel heatexchange apparatus includes relatively and adjaeently grouped tubularair con- 5 duit coils and a tubular oxygen conduit coil, to-

gether with spacing means whereby the respective coil groups aremaintained in uniformly laterally spaced relation concentrically, toprovide passage space for the outgoing and up-flowing movement ofnitrogen gas, and so that this relatively cold nitrogen gas may contactwith the external surfaces of the air tube coils for additional heatexchange effect, while at the same time the uniformly distributedpassage space thus provided for said nitrogen gas will assure continuousflow thereof with a minimum of restriction.

This invention has for a further object to provide a novel constructionand relative dispositional arrangement of a plurality of concentricallyrelated air tube coils, each comprising a single helical tube, and anoxygen tube coil comprising a plurality of helical tubes in' parallel,with certain of the air tube coils being positioned 55 at one side orinwardly of said oxygen tube coil while. the others of' the air tubecoils are positioned at the opposite or outer side of said oxygen tubecoil, thus assuring that substantially equal heat exchange effect isexerted by the intermediately disposed oxygen tube coil upon the out- 5lying air tube coils.

Other objects of this invention, not at this time more particularlyenumerated, will be understood from the following detailed descriptionor the same; I

An illustrative embodiment of this invention is shown in theaccompanying drawing, in which:

Fig. 1 is a vertical longitudinal sectional view of a heat exchangeapparatus according to this invention, portions of the air tube coilsand inter- 15 Q mediate oxygen tube coil being shown in elevation; andFig. 2 is a transverse or horizontal sectional view of said heatexchange apparatus.

Similar characters of reference are employed in said above mentionedviews, to indicate correo sponding parts.

The novel heat exchange apparatus is mounted within the upper end ofarectifying column which is not shown except for a portion of its top endwall, which is indicated by the reference character I. 1

The heat exchange apparatus per se comprises an external cylindricaljacket or casing 2 having a top flange 3, which is secured by bolts 4,or

' other suitable fastening means, to the rectifying column top wall I,so as to depend therefrom.- Suitably secured to said top flange 3 toextend therefrom axially downward within the interior of said jacket orcasing 2 is a cylindrical spool 5, the lower free end of which is closedby a bot- 5 tom cap or end wall'i; By this arrangement, an annularhousing chamber 1 is provided, intermediate said jacket or casing 2 andsaid spool 5, within which the coil groups of the apparatus areconcentrically arranged to extend downward- 40 ly therethrough. Thelowernend of said jacket or casing 2 is open to communication with theinterior of the rectifying column, any suitable means of connectionbeing provided, such as indicated illustratively by the connectingmember 8. The means for conducting the ingoing airv through the heatexchange. apparatus comprises a series of air conduit coils inrelatively concentrically spaced relation 'to extend downwardly throughthe housing chamber 1. Each coil comprises a single helical tube, thehelices of which are of such pitch as to provide some free spacetherebetween so as to permit flow movement of nitrogen between adjacenthelices of the respective conduit coils.

The means for conducting the outgoing oxygen through the heat exchangeapparatus comprises an oxygen conduit coil to extend upwardly throughthe housing chamber 1. This oxygen conduit coil comprises a plurality ofhelical tubes disposed in parallel relation in vertical plane, thehelices of the same being of such pitch that free space is providedbetween vertically adjacent tubes so as to permit flow movement ofnitrogen therebetween. As illustrated in the drawing, the oxygen conduitcoil comprises four tubes 9, I0, ii and 52 disposed in parallel invertical plane; it will be understood, however, that a greater or lessernumber of such tubes may be optionally employed. The lower intake endsof these tubes 8, it, it and i2 are connected with a suitable intakeheader E3, to which is connected the oxygen delivery pipe it which leadsfrom the source of oxygen gas within the rectifying column interior. Theupper outlet ends of said tubes 9, l0, H and G2 are, in similar manner,connected with a suitable outlet header i5, to which is connected theoxygen discharge pipe is through which the oxygen gas generated withinthe rectifying column is finally discharged for delivery to a suitablegas holder (not shown). The advantage of the multiple parallel tube formof the oxygen conduit coil .is that it assures less resistance to thefree and reasonably rapid flow of the oxygen as which is at acomparatively low pressure.

The air conduit coils are respectively designated by the referencecharacters ll, l8, l9 and 20. These air conduit coils run parallel oneto another and in concentric relation, and comprise an inner groupconsisting of the tubes I1 and I8, disposed inwardly of and concentricto the oxygen conduit coil, and an outer group consisting of the tubesl9 and 20, disposed outwardly of and also concentric to the oxygenconduit coil. While four air conduit coils are shown in the drawing, itwill be understood that more or less than this number may be employed,and, likewise, more than one oxygen conduit coil may be employed,according to the size of the heat exchange apparatus required for agiven size and capacity of rectifying column with which it isassociated. The upper or intake ends of the respective air conduit coilsare connected with a suitable intake header 2|, to which is connectedthe air delivery pipe 22 through which the dry compressed air isdelivered to the rectifying column. The lower outlet ends of saidrespective air conduit coils are connected with a suitable outlet header23, to which is connected the air delivery pipe 24 for delivering thecooled compressed airto the expansion valve (not shown) through which itis, in turn, delivered into the rectifying column for liquefication anddistillation.

From the above description and the accompanying drawing, it will beclear that the air conduit coils and the oxygen conduit coil arerelatively disposed in mutually spaced concentric relation. In order tomaintain the concentric spacing uniform between the successive coils, sothat spaces around and between adjacent helices thereof are freelyopento the flow of nitrogen around and contiguous thereto,v verticallyextending spacing strips 25 are engaged between the coil runs, and alsobetween the sides of the jacket or casing wall 2 and spool wall 5 andthe coils respectively adjacent to these walls.

The comparatively cold nitrogen gas, which is formed within and risesthrough the rectifying column, flows through the member 8 upwardlythrough the spaces intermediate the coil runs as well as between thehelices of the individual coils, thus contacting the walls of the airconduit tubes so as to materially aid in the transfer of heattherethrough from the air flowing downwardly through said air conduitcoils. Any suitable form of nitrogen'outlet means, as 26, is connectedin communication with the upper end of said housing chamber 1.

It will be obvious that various changes could be made in the abovedescribed constructions, and that apparently widely differentembodiments of this invention could be made without departing from thescope thereof. It is therefore intended that all matter contained in theabove description or shown in the accompanying drawrel tending throughsaid housing chamber interior to conduct outgoing oxygen for dischargefrom said rectifying column, said air and oxygen conduit coils beingarranged in concentric closely spaced relation with some of the airconduit coils disposed inwardly of and adjacent to and some outwardly ofand adjacent to the oxygen conduit coil, all arranged so that nitrogengas may flow contiguous to and in contact with all air and oxygenconduit coils, and spacer means to maintain said coil runs uniformlyspaced concentricallyto provide passages for the flow movement ofnitrogen therebetween and contiguous thereto.

2. In heat exchange apparatus as defined in claim 1, wherein said oxygenconduit coil comprises a plurality of tubes having their helicesparallelin vertical plane.

. 3. Heat exchange apparatus for the purposes described, comprisingmeans to provide an annular housing chamber arranged to receive, foroutgoing movement therethrough, nitrogen gas discharged from arectifying column, an up-flow.

oxygen conduit coil extending through said housing chamber interior toconduct outgoing oxygen for discharge from said rectifying column, saidoxygen conduit coil comprising a plurality of tubes having their helicesparallel in vertical plane, header means with which the inlet ends andoutlet ends of said tubes respectively connect, a series of air conduitcoils each comprising a single tube extending through said housingchamber interior to conduct ingoing compressed air to-the interior ofsaid rectifying column, said air and oxygen conduit coils being arrangedin concentric closely spaced relation, with some of the air conduitcoils inwardly and some outwardly disposed relative to saidoxygenconduit coil, all

arranged so that nitrogen gas may flow contiguous to and in contact withall said air and oxygen conduit coils, header means with which the inletand outlet ends of said air conduit coil tubes respectively connect, andspacer means to maintain said coil runs uniformly spaced concentricallyto provide passages for the flow movement of nitrogen therebetween andcontiguous thereto.

. PETER. PEFF.

